1. Field of the Invention
A pump drive apparatus according to the invention is installed within a basement of a building and is used to pump water to be used in this building up to a water tank installed on the rooftop of the building. Or, a pump drive apparatus according to the invention can also be applied to various uses: that is, it is used to pump water up to a reservoir or a water vessel for an agricultural use or for an industrial use.
2. Description of the Related Art
For example, in the case of a building, it is impossible to supply water directly to the high floors of the building with the pressure of the water flowing through a water pipe. For this reason, in the case of an ordinary building, a water tank and a water pump are installed in the basement of the building, while the water that has been poured into the water tank from the water line is moved to another water tank installed on the rooftop of the building using the water pump. The water to be used within the building is supplied to the respective floors from the water tank installed on the rooftop using the water head pressure. By the way, as a pump which is used in this case, generally, there is used a pump of a turbo type such as a centrifugal pump, a diagonal flow pump, and an axial flow pump (especially, the centrifugal pump).
Also, as a method for changing the quantity of water to be supplied to the water tank on the rooftop of the building using the above-mentioned water pump, conventionally, for example, as stated in a book which is titled xe2x80x9cFluid Machinery Handbookxe2x80x9d and is published by Asakura Shoten Co., there are known the following methods (1)-(3).
(1) A method for changing the opening angle of a flow control valve interposed between a water pump and a water tank.
(2) A method for arranging a plurality of water pumps in parallel to one another and changing the number of water pumps to be operated at the same time.
(3) A method for changing the rotation speed of an electric motor which is used to drive and rotate a water pump.
Of the above three methods (1)-(3), in the case of the method (1), when the water supply quantity is reduced down, the energy that is necessary to operate the water pump is used wastefully. That is, as pointed out in the above-mentioned book xe2x80x9cFluid Machinery Handbookxe2x80x9d as well, even in case where the opening angle of the flow control valve is decreased in order to reduce the water supply quantity, the power necessary to drive the water pump cannot be reduced down to a sufficient degree that can reduce the water supply quantity; and, therefore, the energy corresponding to the power is used wastefully.
Also, in the case of the methods (2) and (3), there arise some problems: that is, because a plurality of water pumps which can be operated at the same time must be disposed, the installation cost of the water pumps is high and there is required a large space for installation of the water pumps (in the case of the method (2)); and, since it is necessary to control and rotate an electric motor having a large output, there is required a large-size inverter, which results in the increased cost (in the case of the method (3)).
The present invention aims at eliminating the problems found in the above-mentioned conventional pump drive apparatus. Accordingly, it is an object of the invention to provide a pump drive apparatus in which, while the downstream-side flow passage of a water pump is not tightened by the flow control valve, but a drive source such as an electric motor is operated at a constant speed, and the water supply quantity can be controlled by changing the operating speed of the water pump, whereby in case where the water supply quantity is reduced, the energy efficiency thereof can be enhanced.
According to a first aspect of the invention, in attaining the above object, there is provided a pump drive apparatus comprising a drive source, a pump to be driven and rotated by the drive source, and a toroidal-type continuously variable transmission interposed between the pump and drive source.
Also, according to a second aspect of the invention, in the present pump drive apparatus, the drive source includes a drive shaft, the pump includes a rotary shaft, the toroidal-type continuously variable transmission includes an input portion and an output portion, the drive shaft of the drive source is connected to the input portion of the toroidal-type continuously variable transmission in such a manner that the rotational force of the drive shaft can be transmitted to the input portion, and the output portion of the toroidal-type continuously variable transmission is connected to the rotary shaft of the pump in such a manner that the rotational force of the output portion can be transmitted to the rotary shaft.
And, according to a third aspect of the invention, the above input portion is an input shaft and the above output portion is an output gear.
Further, according to a fourth aspect of the invention, between the drive shaft and input portion, there is interposed an accelerator; and, between the rotary shaft and output portion, there is interposed a decelerator.
And, according to a fifth aspect of the invention, there is provided a pump drive apparatus comprising a drive source and a pump to be driven and rotated by the drive source, wherein, between the pump and drive source, there is interposed a continuously variable gear change apparatus; and, the continuously variable gear change apparatus is composed of a toroidal-type continuously variable transmission and a planetary gear mechanism.
And, according to a sixth aspect of the invention, in the above pump drive apparatus, the drive source includes a drive shaft, the pump includes a rotary shaft, the continuously variable gear change apparatus includes an input shaft and an output shaft, the drive shaft of the drive source is connected to the input shaft of the continuously variable gear change apparatus, the output shaft of the continuously variable gear change apparatus is connected to the rotary shaft of the pump and, between the input and output shafts, there are interposed a toroidal-type continuously variable transmission and a planetary gear mechanism.
And, according to a seventh aspect of the invention, the input and output shafts are disposed concentrically with each other.
Further, according to an eighth aspect of the invention, the above pump drive apparatus further includes a first power transmission mechanism for transmitting power input to the input shaft through the toroidal-type continuously variable transmission, and a second power transmission mechanism for transmitting power input to the input shaft not through the toroidal-type continuously variable transmission.
And, according to a ninth aspect of the invention, in the above pump drive apparatus, the planetary gear mechanism includes a sun gear, a ring gear disposed on the periphery of the sun gear, a planetary gear interposed between the sun gear and ring gear, and a carrier for supporting the planetary gear in a rotatable manner.
And, according to a tenth aspect of the invention, the planetary gear mechanism is disposed laterally of the toroidal-type continuously variable transmission.
Also, according to an eleventh aspect of the invention, between the output portion and rotary shaft, there may be interposed a joint which can be freely engaged and removed.
Further, according to a twelfth aspect of the invention, between the output shaft and rotary shaft, there may be interposed a joint which can be freely engaged and removed.
Moreover, according to a thirteenth aspect of the invention, in the intermediate portion of the first power transmission mechanism, there may be disposed a joint which can be freely engaged and removed.
In a pump drive apparatus having the above structure according to the invention, while a drive source such as an electric motor or an engine is being operated at a constant speed, by changing the gear change ratio of a toroidal-type continuously variable transmission or a continuously variable gear change apparatus, the operating speed of the water pump can be changed to thereby be able to control the quantity of water to be supplied by the water pump. Therefore, the water supply quantity can be made substantially proportionate to the energy that is required for operation of the water pump, thereby being able to avoid the wasteful energy consumption. Also, since there are eliminated the need for provision of a plurality of water pumps to be operated at the same time as well as the need for provision of a large-size inverter, neither the installation cost nor the installation space can be increased.
Further, in a pump drive apparatus according to the invention, since there is reduced the torque that is applied to a toroidal-type continuously variable transmission to be incorporated into a continuously variable gear change apparatus, even under such severe operating conditions that the pump drive apparatus is continuously operated for a long time under high loads, the durability of the toroidal-type continuously variable transmission can be secured sufficiently.